In most cases, rolling your own Perl does not require an inordinate amount of work. I refer to you to Perlbrew and cpanminus, both of which can be potentially life-changing.

The benefits of running your own Perl go beyond the new language features (which are significant between 5.10 and 5.18; see perldelta for more information). By running your own Perl, you gain complete control over what you upgrade, and when you upgrade. OS Perl releases are often for the benefit of the OS itself: to support scripts used by the particular Linux/UNIX distribution you run, so those releases tend to lag pretty far behind. In this case, five and a half years! The releases are often patched as well, either to backport bug fixes, or for other reasons. Hence, you are not running vanilla Perl.

For these reasons, you will often have trouble installing CPAN modules, and are often faced with the dilemma of whether to use the (older) RPM provided by your Linux distribution, if anyone bothered to package it at all, or abandoning it entirely if it won't install via CPAN due to incompatible dependencies or Perl version.

Running your own Perl will fix these issues, but note that any Perl modules that depend on C/C++ libraries may still cause problems if the RedHat versions lag too far behind. Staying with the OS Perl and OS-packaged mods usually avoids this issue by keeping all the versions in sync even if they're old, or not providing packages for newer modules.

Nothing's perfect, but once you get past the fear of the unknown and acclimate to the perlbrew process, many headaches go away.

That being said, upgrading the programming language (or its modules) that underlies a large programming project is not something to be done on a whim, as interfaces can change, subtle changes can cause bugs (such as the hash order randomization change), and other unexpected problems can occur. That is not to say that upgrading isn't worth it, but you would be well-advised to have a fallback plan, and an excellent suite of unit tests and manual test plan to quickly find any regressions.